An annulus can be approximated by two n-sided boundaries with the same center, but different radius.
In geometry, a polygon with holes is an area-connected planar polygon with one external boundary and one or more interior boundaries (holes).[1] Polygons with holes can be dissected into multiple polygons by adding new edges, so they are not frequently needed.
An ordinary polygon can be called simply-connected, while a polygon-with-holes is multiply-connected. An H-holed-polygon is H-connected.[2]
- ^ Somerville, D. M. Y. (1929), "IX.4: Polyhedra with ring-shaped faces", An Introduction To The Geometry Of Dimensions, Methuen & Co., pp. 144–145
- ^ O'Rourke, Joseph (1987), "Chapter 5: Holes" (PDF), Art Gallery Theorems and Algorithms, International Series of Monographs on Computer Science, vol. 3, Oxford University Press, pp. 125–145, ISBN 0-19-503965-3
